This invention relates in general to the aeration of liquids such as water and waste water and deals more particularly with an improved structure for mounting air diffusers on air supply piping.
In the aeration of waste water and other liquids, it is common practice for air diffusers to be installed in the treatment basin which contains the liquid. Submerged air supply laterals receive air and apply it to diffusers which are connected with the laterals. The diffusers then discharge the air into the liquid in the form of bubbles. The highest efficiency aeration is achieved by using fine bubble diffusers such as porous membrane diffusers. However, less expensive coarse bubble diffusers are also used in some applications.
The diffusers can be connected to the supply piping in a variety of ways. When relatively long diffusers are used, as is becoming increasingly common in recent years, considerable leverage is applied by the diffusers. Consequently, the diffusers must be connected to the air laterals in a structurally sound manner in order to prevent breakage of the connection and other problems.
U.S. Pat. No. 4,960,546 to Charles E. Tharp discloses a diffuser mounting arrangement that has functioned well for the most part. The halves of a two piece saddle are fitted closely around the air lateral to provide a double wall thickness at the location where the diffuser connects with the lateral. This construction has proven to be strong enough to withstand the considerable forces that are applied by lengthy diffusers.
However, the patented system has not been ideal in all respects. A separate Tee fitting is needed, and this increases the component costs and also the labor costs due to the need to solvent weld the various parts together. Further, the diffusers are offset from the air lateral by the length of the Tee fitting. Therefore, the laterals must be spaced above the floor of the basin in order to accommodate diffusers that are mounted below the laterals, and this is a significant disadvantage in installations where it is desirable to locate the laterals as close to the floor as possible. Because both diffusers are connected to the Tee, the cantilever forces generated by both diffusers when the system is in operation are applied to the Tee and are concentrated at its connection with the saddle outlet spout. This concentration of forces at a potentially weak area of the system can create structural failure.
Perhaps even more importantly from a practical standpoint, it is necessary with the patented Tharp arrangement to connect both diffusers to the Tee fitting (and to one of the saddle sections) at the factory and then ship this assembly to the job site. The double diffuser assembly is an unduly long unit that includes two diffusers that may together be 3 meters long or more, together with the Tee fitting and saddle section. Long rigid crates are required for the packing of this assembly, thus adding significantly to the shipping costs. Moreover, the Tee fitting and saddle jut to one side at the center of the assembly and must fit in the crate, so there is a large volume of wasted space in each crate. The shipping costs are increasingly important when shipping distances are great such as in the case of overseas shipping.
U.S. Pat. No. 4,960,546 contemplates saddle units and Tee fittings that are standard commercially available products. Thus, each saddle and Tee assembly is useful with only a single pipe size used to form the diffuser body. Because there are different applications where different diffuser pipe sizes are necessary or desirable, the saddles and/or Tee fittings must be provided in different sizes. The inventory costs are increased accordingly.
The present invention is directed to a diffuser mounting assembly that is improved in a number of respects over the mounting arrangements that have been used in the past.
In particular, the diffuser mounting assembly of the present invention eliminates the need for a separate Tee fitting and the drawbacks associated with it. This is accomplished by providing specially constructed saddles that have integral outlet fittings to which the diffusers can be directly connected by solvent weld or otherwise. A number of important benefits are achieved by this construction.
First and perhaps most notably, the units can be packaged and shipped in two pieces, with each piece including one saddle section and one diffuser. The result is that the shipping carton is less than half as long as in the case of two diffusers and a Tee fitting all connected in line. The dramatic reduction in length allows cardboard cartons to be used instead of the rigid crates needed for longer units. This allows less expensive packaging products and decreases the time required to pack and load the units.
Elimination of the Tee fitting also allows the diffuser units to be placed side by side with the saddle sections overlapping the ends of the adjacent diffuser in alternating fashion. As a result of this, the space required to pack the diffusers is decreased by about 30% compared to units having Tees and saddles jutting out at the center of a double diffuser assembly. The shipping cartons can be provided with cardboard dividers between the diffusers so that the relatively fragile diffuser membranes are protected by cardboard on all sides. Standard designs and inventory can be used and can be quickly and inexpensively shipped.
Another feature of significance is the eccentric location of the outlet fittings on the saddle sections. The outlets are preferably located with their bottom surfaces at the same level as the bottom surface of the laterals. Accordingly, both the laterals and diffusers can be installed essentially on the basin floor. Maximizing the depth of both the laterals and diffusers is highly advantageous in many applications, as the air is released at the full basin depth to achieve maximum aeration.
The invention is further characterized by saddle outlet fittings that are specially constructed to closely receive one standard pipe size (for example, a 4 inch diameter pipe) on the outside and a smaller standard pipe size (for example, a 3 inch diameter pipe) on the inside. This allows one unit to accommodate two different diffuser body sizes and thus enhances its versatility and avoids the need to inventory different units for each different diffuser size.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.